"What was the velocity of Pioneer 10, Pioneer 11, Voyager 1 and Voyager 2 at some point (lets pick up 25 AU for it is past the Voyager 2 gravity assists) and what will be the velocity of NH at the same point?"

This will be a better question and we will see how many % is the difference of the velocities of these spacecraft. Actually I was looking for Emily's thread for Q&A yesterday in order to submit this question for the Planetary Radio, but I couldn't dig it out.

The two Helios approached closer to the Sun than Messenger, and may have a higher orbital velocity at perihelion.

Yes, Helios II should still hold the recordspeed of 252.792 km/h (70,2 km/s) at a minimum distance of 43,4 Millionen km from sun.This is about 0,0234% of the speed of light. So we are a bit far away from useful interstellar travel speeds...

Atanas, the following web-page and graph would give you an impression on how the 5 solar system leaving crafts are faring, distance over time, but doesnt give speed. Anyway, what you'd want to know is speed at infinity (from the Sun), i.e. the speed the probes will have when the Sun has no more gravitational influence on them.

I would like to know the current location of the star motor upper stage please

I found the following source about the upper stage motor. It's actually ahead of NH since the first NH TCM slowed it down a little, at least up to Jupiter, but there received less "kick" than the spacecraft did, so that NH will catch-up and overtake its engine (in a way)

And now with calculations, using(1) a = semi-major axis from the SSD Horizons system (date set for today, reference set to solar barycenter)and using (2) v_infinity = square root of ( G * M_sun / |a|) [as per Greg's reference]

As NH is about to pass the orbit of Saturn: if Saturn was to be found in it's orbit in the path between the current NH position and the outer course, would NH then have then crashed into Saturn or it would have flown 'north' or 'south' of Saturn (ignoring any gravitional pulls) ?

As NH is about to pass the orbit of Saturn: if Saturn was to be found in it's orbit in the path between the current NH position and the outer course, would NH then have then crashed into Saturn or it would have flown 'north' or 'south' of Saturn (ignoring any gravitional pulls) ?

General hand-waving answer: Since Pluto is inclined significantly from the ecliptic, NH has to gradually make that journey from Jupiter (near the plane) to Pluto (not near the plane). Saturn's diameter is microscopic compared to the distance above/below the plane that Pluto occupies at almost all times of its orbit. There's no way it would happen to strike Saturn, although I'm sure that it would gravitationally warp the trajectory significantly if it happened to be within a fraction of an AU.

Infocat-- Since you asked, I had a propper analysis done. See attached.

Beautiful! I'll add information gathered from those slides to my (planned) New Horizons' script, once I'm done working on the Phoenix real-time simulation script ... if I may do so, of course. Good luck Alan with NH!

Milestones Ahead: New Horizons Set to Cross Saturn’s OrbitSpacecraft Will Be First to Journey beyond Ringed Planet Since 1981

Last week, New Horizons woke up from its longest electronic hibernation period to date — 89 days. And over the next 10 days, the New Horizons team will celebrate a trio of milestones on the spacecraft’s long journey to explore Pluto in 2015.

The team roused New Horizons from hibernation mainly to re-point the spacecraft’s antenna, adjusting to the changing position of Earth around the Sun. The operations team is also carrying out navigation-ranging tests that mimic operations at Pluto, as well as conducting additional tracking, downlinking data from the student dust counter instrument, installing and testing bug-fix software for the SWAP solar wind plasma instrument, and uploading the spacecraft flight plan for the next several months. These activities will be complete by June 2; the next day, New Horizons will re-enter electronic hibernation for another 91 days. It will awaken for its annual checkout on Sept. 2.

New Horizons reaches the first milestone just before going back into hibernation. On June 2, the spacecraft will be 10 Astronomical Units (AU) from the Sun. One AU is the distance from the Earth to the Sun, about 93 million miles (or 149 million kilometers). New Horizons will be 930 million miles, or just about 1.5 billion kilometers from the Sun.

On June 3, the mission team will celebrate the spacecraft’s 866th day in flight – or one-quarter of its 3,463-day (9.5-year) journey to Pluto. New Horizons will pass its halfway mark to Pluto in another 866 days, on Oct. 17, 2010.

Most notably, however, on Sunday, June 8, the spacecraft will cross the orbit of Saturn, though Saturn itself is nowhere near the course New Horizons is following to Pluto. “This milestone is significant because the last time any spacecraft journeyed beyond Saturn was 27 years ago, in August 1981, when Voyager 2 passed Saturn on its way to encounters with Uranus and Neptune later in the 1980s,” says New Horizons Principal Investigator Alan Stern.

After New Horizons passes the distance where NASA’s Cassini orbiter is operating at Saturn, only two spacecraft will be operating farther out than the Pluto-bound probe. These are NASA’s Voyagers 1 and 2, which are at the edge of the Sun’s heliosphere approximately 100 AU away.

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